Roasting furnace



sept. 2 1924. 1,5%,942 R.- n'. PIKE ROASTING FURNACE VFil'd Nov. I9-,1923 yao Patented Sept. 2, 1924.

UNITED STATES lamiizl N ROBERT n. PIKE, on sAN FRANCISCO, CALIFORNIA,

.noAsTING FRNACE.

Application mea November 19,1923'. seiaiNoJevae/ivi v To all whom t maycof/wem.'

Be it'known that l, ROBERT D. PIKE, a

citizen of the United States, residing at city v and county of SanFrancisco, and State of California,`have invented certainnew and usefulImprovementsin a Roasting Furnace, of which the following is aspecification.V I The hereinafter' described invention relates tocooling means or means for maintaining circulation of air through therabblingy mechanism of multiple hearth mechanical roasting furnaces andmore especially, those' in which highly endothermic reactions arecarried at relatively high temperature. In this class of furnaces thetemperature maintained in the lower part is exceedingly hig'h andrequires the incorporation within the furnace of more highly efficientcooling means than provided for at the presenttime and for theaccomplishment of the purposes desired the cooling means are required tobe of such a form as will combine an efficient cooling of the metal ofthe rabbling mechanism with a minimum labstraction of heat from thefurnace. l

The present type of ore roasting furnaces tov which this invention `ismore particularly applicable are provided witha rotating column formedof two concentric members, to the outer one of which the rabble arms areattached. These members of the column arev so arranged as to take freshair for cooling of the rabble arms into. thecentral duct of the rotatingcolumn at the bottom thereof, which air ascending therein passes intoand through the rabble arms in parallel, each rabble arm receiving freshcooled air from the rotating column and each discharging heated airyinto the annular duct thereof through whichitrises and passes out ofthe top of the column.` Under this construction the only air whichpasses Athrough the annular duct of the central rotating column is airwhich has been heated by passing 4through and discharging from therabble arms, no provision being made foi-,causing a flow of air for thecooling of the outside metal of the centrally disposedv rotating columnat the lowerend portion thereof and which it is essential to protect.The construction of such a form of centrally dis- 'posed rotating columnutilized in a multiple Ahearth mechanical roasting furnace is fully setforth and describedin my United States Letters Patent No. 1',166,38v'12,' dated ,August 28th, 1923. i

By my present invention'meansare provided atLor adjacent thebottom ofthec'entrally disposed rotating column'jand Vsubstantially yat a level withthe bottom hearth ofthe furnace forfpermitting 'a by-passing of aregulatedquantity ofl cool air directly from the central duct of therotating column into. the annular duct thereof,said'by-passing of theair being controlled by means external to the furnace and which permitsof.

the air passing directly to the annular duct and such of the air as isconstrained topass through the rabb'hng arms to be regulated at the willof the operator. y v

For an understandmgof rthe invention, reference should be had to theaccompanying sheetof drawings wherein is illustrated.

a broken vertical sectional view of `a multiple hearth roasting furnacewith'my invention applied thereto. .In the drawings the numeral 2'isused todesig'nate a multiple hearth mechanical roasting furnace which isprovided with a centrally disposed .rotat-l ing hollow`column,vwhichcolumn supports the hollow rabble arms 3 disposed to work 'over theseveral hearths 4; arranged 1n superposed relation within the furnace.'The cen- *to the outside atmosphere by thepartition wallS, and innerlorcentral ductf" of saidrotating column is closed at itsupp'er end or topby the cover-,wall or partitioir plate 9, only allowing for-a passage'therethrough of a centrally disposed rotatable rod 10i. At its upperend the outer annular space vfof the rotating column communicates withthe outside throughvthe medium of slots '11' in communication withaninterior chamber 1Q,

of a lixedho'usingl, with which housing.

connects an outlet pipe 13. A bearing 111 supported on structural member'15 supports ,o1-'upholds the housing 12', which housing has a centralpassage in the bottom wall thereof through which is extended therestricted portion 16 of the outer' shelly 5 of the rotating centrallydisposed column. The rotatable rod passes through an aperture formed inthe top wall 17 of the housing 12 and held in place by an inwardlydisposed collar 18 bearing against the under face of the cover plate 17and a lock nut 19 applied outside of the cover 17. The lock nut 19 inconjunction with the collar 18 serves tohold the rotatable rod 10securely in locked position, but when the lock nut 19 is loosened therod 10-is free to be turned by the handle 2O relative to the centralcolumn, which relative position of the rod can then be fixed or securedby a tightening of the lock nut 19. The said rotatable rod 10 issupported with respect to the central duct 6 by means of the spiders 21suitably spaced within the innerA shell 6 of the centrally dis posedrotating column.

The inner shell 6 terminates at its lowered end extended below7 ltheroasting furnace in a bottom pin 22, which seats within a bearing 23 androtates within a body of oil 24: contained therein, the whole beingsupported on a suitable foundation 24a. Air under pressure is admittedfrom a suitable outside source through the supply pipe 25 into a chamber26 surrounding the lower portion of the central shell 6 and flows fromsaid chamber 26 within the shell 6 through the inlet openings 27 formedin that portion of the said shel situated within the chamber 26. Rotarymotion is transmitted to the centrally disposed column through themedium of the gear 28, which meshes with a pinion 28a driven from anysuitable source of power. Y

A regulated portion of the cooling air passing upwardly through theinner shell 6 makes its escape from within the central duct 6 into theannular passage 5 through outlet ports 28', suitably situated in thewall of the inner shell 6 and that portion thereof on a levelsubstantially corresponding with the level of the bottom hearth 29 ofthe furnace. The passage of the air through the outlet ports 28 isregulated or controlled by v the position of the slotted cage 30attached to the rotatable rod 10 at the lower end thereof, thecircumferentially disposed slots or ports 30 of which correspond withthe outlet ports 28 of the central shell 6. As the rod 10 is rotatablerelative to the shell 6, the area of the passage between the inner duct6 and the annular passage 5 of the centrally disposed rotating columnmay be varied from the full area of the outlets 28 to Zero, dependentlentirely upon the positioning of the ports 30 of the cage 30 withrespect to said outlets 28.

Such of the cooling air as does not pass directly from the duct 6intothe annular space 5 of the central column moves upwardly within theduct 6 and escapes therefrom through the spaced ducts 32 of the shell 6into the hollow rabble arms 3 and after circulating therethrough for acooling thereof, discharges therefrom into the annular space 5 throughthe inlet openings 38 formed in the wall of the shell 5 and whichcommunicate with the interior of the hollow rabble arms 3, thencepassing upwardly makes its escape from the centrally disposed columnthrough the outlets 11 into the chamber 12 of the housing 12.

Through the use of the described invention the operator is enabled todivide a given i stream of cooling air entering into the apparatus rfromthe air supply conduit 25 into two streams of regulated proportions, onestream passing directly into the annular passage 5 for eectively coolingthe metal walls thereof and the other lstream flowing upwardly withinthe shell 6 being utilized for the cooling of the rabble arms, therebyenablingv a more efficient cooling of the central rotating column at thebottom thereof and within the Zone of maximum heating than is ipermitted under present construction and at the same time I am enabledto effectively cool the entire central column independently of thecooling of the rabble arms.

lhile I have illustrated and described the invention in its preferredembodiment, I do not wish to be understood as confining or restrictingmyself to the details of construction of working parts as illustratedand def scribed but wish to be understood as claimingthe invention asbroadly as the state of the art will warrant.

Having thus described my invention, what rotating central column,composed of spaced concentric shells providing an inner air duct and anouter annular air duct, means for introducing air into the lower end :ofthe inner air duct and for5 escape of air from the upper end of theouter annular air duct` of the rotating column, hollow rabble armssecured to and carried by the central column, connections for passingcoolingair from the inner air duct ofthe column into the rabble arms andconnections for delivering air from the rabble arms into the annular airduct of said column, and means at the approximate lower level of thefurnace for passing cooling air direct from the inner air duct of therotatingcolumn into the outer annular airduct thereof.

2. Ink combination with a multiple hearth furnace, a centrally' disposedrotating column mounted therein and comprising spaced concentric shellsproviding an inner air duct and an outer annular' air duct, means foradmitting cooling air into the inner shell yof no f the column, outletports formed in the Wall the flow of air from the inner air duet into ofthe inner shell adjacent the lower end the outer annular air duct of thecentral thereof, means Within said shell for controlcolumn. 10 ling theflow of air through the outlet ports In testimony' whereof I have signedmy 5 thereof into the annular air duct of the 10- name to thisSpecification.

tating column, and manually operated devices for actuating said meansfor regulating ROBERT D. PIKE.

